Geomag is one of those wonderful products that fits in the geek toy niche in the shopping food chain.
Simply, Geomag consists of ball bearings and magnetic rods. The rods are plastic, roughly cylindrical (actually they're hexagonal prisms), about 3cm long, and 0.5cm diameter. At each end is a slightly indented metal surface. Inside each rod is a magnet. A very very strong magnet. The ball-bearings are about 1cm diameter, and fairly standard.
Can you see where this is going? You put the balls and the magnetic rods together to make shapes. That's it. Boring, no?
Well, not at all actually. The rods act as vertices, the balls as corners and intersection points, with several rods attached to the same ball. With 6 rods and 4 balls you can make a little triangular pyramid. And the thing is rigid, hard, a brand new object.
As with any good toy, the possibilities are endless. Complex geometric shapes can be easily constructed and destroyed. The rods can move around the balls unless they are structurally constrained, so 'bendy' shapes are possible, too. The rods can stick end-to-end to each other, and can also stick end-to-middle. And lastly, two balls can stick to each other, provided both are magnetized appropriately by the rods. This ball-to-ball join has a tiny contact area, so very low friction. A structure can be suspended and spun in this way.
Geomag isn't cheap, though. Buying the stuff can be a difficult decision as different packs have a different ratio of rods to balls. The smallest pack (6 rods, 8 balls) is about £5 or $7. The biggest has 1000 bars and 450 spheres, and is $800. The rods come in a variety of colours; some packs are monochrome, some are mixed, and some are glow-in-the-dark. Geomag won a whole host of 'new toy' awards in 2002. Oh, and the name presumably comes from the words Geometry and Magnet.
I love this stuff. I don't have very much, enough for a 2-rod wide pyramid. But it's fun to play with magnets, and it's fun to make stuff. Geomag combines the two in a clean and sort of stylish
Some toy shops carry Geomag, and so do online stores:
www.svgames.com/geomcon.html has the full selection (in the USA)
www.firebox.com has one set (in the UK).